Optical Chopping Enhanced Rydberg-Atom-Based Ultra-Low-Frequency Electric Field Measurement

TL;DR

This paper introduces an optical chopping amplification technique that significantly enhances the sensitivity of Rydberg-atom-based ultra-low-frequency electric field measurements by reducing 1/f noise through modulation and demodulation, broadening the sensor's effective frequency range.

Contribution

The study presents a novel optical chopping amplification method that improves Rydberg sensor sensitivity for ULF electric fields by shifting noise to higher frequencies for better filtering.

Findings

Sensitivity improved by 19.1 dB at 7 Hz

Detection range extended from low frequency to ULF

Nearly 7 dB enhancement from 10Hz to 1kHz

Abstract

This study demonstrates a significant enhancement in ultra-low-frequency (ULF) electric field sensitivity using Rydberg atoms via an optical chopping amplification (OCA) technique. Conventional Rydberg-based ULF measurements are fundamentally limited by 1/f noise, which severely degrades sensitivity. Our approach modulates the coupling laser with an optical chopper before the vapor cell, inducing periodic Rydberg excitation at the chopping frequency. The photodetector (PD) output signal is demodulated by a lock-in amplifier (LIA) using the optical chopper's signal as the reference. This process effectively improves the signal-to-noise ratio (SNR) by shifting the 1/f noise to a higher frequency band where it can be filtered out. The OCA technique enhanced sensitivity by 19.1 dB for the frequency 7 Hz, which is down to 49.1 uV/cm/rt(Hz). For the frequency range from 10Hz to 1kHz, it also enhanced nearly 7dB. This OCA method for enhancing the sensitivity of Rydberg atoms in ULF electric field measurements enables the Rydberg sensor's detection range to span the entire spectrum from low frequency (LF) to ULF, thereby significantly broadening its application potential.